This kind of knowledge
by Docnerd89
Summary: When she finally met his eyes, there was such conviction that he knew he'd be powerless if she asked him to stop shadowing her. Her face wore a sort of furious determination, her eyebrows low, her jaw clenched. (AU, post Setup/Countdown)
1. Chapter 1

Rick Castle used to be a jackass. Not all the time, no. But most times, with most people. He used to be pompous, callous, narcissistic – and, okay that was enough mean introspection. But there was no denying it. He had become aware of these things.

He'd come to realize that there were a lot of things he didn't know.

Take for instance, Kate Beckett. Dissecting her life was something of a pastime for him. To be fair, he knew a good deal about her. She wasn't an easy person to get to know. You only knew as much about her as she would let on. He thought he might know more about her than a few important people in her life combined did – and that was a great thing. To him, that was a great honor. But she'd inadvertently proven him wrong in the past. Proven him wrong because every time he thought he had her down, she'd surprise him. She was a mystery. _Oh, so many layers to the Beckett onion. How ever would he peel them all?_

He knew her, but he also didn't. She was the best confusion of his life.

Three weeks had passed since they'd survived being locked in a freezer. They'd survived almost being blown to death. He'd never thanked his ridiculously hopeful nature more than when he recklessly stuck his hand into the circuit of a bomb and yanked all the wires. Sweet Jesus, they'd survived a bomb. He saved the city. And got a hug for it.

It wasn't surprising then that he'd been having nightmares. Like clockwork, every night since, he'd been having nightmares. The first night he woke up covered in sweat, and he wanted to call her. He really did. Instead he went to his kitchen to fetch himself a glass of water.

Alexis had seen him then, and he must've looked pale because she looked worried and tried to pry. He told her parts, but not everything. He'd like to keep her safe and cushy in her little bubble as long as he could, thank you very much. He thought he managed to assuage her concerns, but promised himself that he would try not to let it show.

He managed to fulfill that promise as far as Alexis went. Trained detectives weren't as easily fooled. Especially not his very formidable trained detective to happened to be fantastic at interrogations. The first few days, Beckett said nothing. But on the fourth day he probably had giant dark circles, and was slurring his words. He thought, when she pointed these things out, that she would be irritated. Annoyed that he was distracted at his non-work. She wasn't annoyed. It was concern. And that made him confess.

He hadn't been sleeping. Like clockwork, every night since the incident, he told her, he'd been having nightmares. They wouldn't always be the same. Sometimes he'd die in the freezer and his nightmare was just a blanket of darkness descending on him. Other times she would die in his arms and those, he told her, were the worst ones. Or it was just like what had happened – except the bomb would start beeping just after they'd hugged, and then – and then nothing. Sometimes, and he was ashamed of this one. Sometimes he'd dream about the time her apartment blew up. He'd break down the door, and he'd call out, looking for her in every room. But she wasn't there. He'd go to the bathroom, with the giant bathtub, his subconscious mind pulled there by his memories – and she would be there. Frozen amidst the flames. Cold and blue and lifeless.

If the concern had thrown him, then her reaction to his confession had completely blown him away. No pun intended. She just nodded in understanding, her eyes downcast. He wondered fleetingly whether the nightmares had been plaguing her too. Nah. Not his Beckett. Not his formidable, unshakable detective.

His? He really needed to have a good sleep soon.

When she finally met his eyes, there was such conviction then that he knew he'd be powerless if she asked him to stop shadowing her. Her face wore a sort of furious determination, her eyebrows low, her jaw clenched. Castle's cowardice had no place in her precinct. Beckett needed a hardened detective for a partner, not this whimpering writer who woke every night shaking thanks to some dreams. Kate needed someone she could count on.

He'd be powerless to deny her anything. With equal conviction lacing her voice, she managed to finagle a promise out of him. A promise to call her, even if it was the middle of the night, if he had the nightmare again.

That's how it had started.

The first time he called her, he did so reluctantly. He contemplated breaking her promise. Letting her sleep. Why share his troubles? But he called her. Just the once, he thought. It would be nice to hear her voice. Losing her seemed to be at the crux of his nightmares. He wondered if she realized that too. He called, and didn't have to wait long before she answered. Soft and beautiful, even half asleep. Half awake. Half Beckett, half Kate. Her voice was strong, but melodious in his ears, completely overpowering the whoosh of his own pulse.

Like clockwork he'd get the nightmare, he'd wake up, call her, and she would answer. Each night she seemed more awake. Each night, he thought, just the once.

Two nights ago, he didn't call her. He didn't wake up. He had managed to sleep through the night. He saw Kate's message before work. It had come around an hour after the time he would usually wake up with a nightmare. It just asked him if he was okay. He hadn't heard his phone buzz. When he saw her yesterday, she looked like she hadn't slept. But she gave him the most beautiful smile when he told her he slept through her message. She joined her hands, and held them close to her chest, as if in silent thanks to a greater being. He thought, just for a moment, that she held them close in lieu of holding him close.

Later when they were at her desk, reviewing the timeline for their latest case, he turned to her. She was staring at the white board with a look of determination. Her brow was furrowed in concentration, as she nibbled on her bottom lip. He felt himself sway just a few millimeters towards her, drawn by a force he couldn't see. Couldn't name. But he could feel it. Boy, could he feel it.

Absurdly he wanted to ask her a billion questions.

Questions that made no sense and made a helluva lot of sense. Questions like, _what makes you want to smile, Kate? Or what side of the bed do you sleep on? _

_What's your favorite picnic spot?_

_What's your fondest memory growing up?_

_Do you know the answers to life, Kate?_

_Do you know what it'll be like to be married to someone you love? Someone who loves you? Do you know how to be married forever? _

_How do you read me? How do you see me? _

_How are you so good? So good, and kind, and wonderful?_

_Do you know what makes the sun burn? The earth turn? _

_Do you know how you're the axis? You have been for a while now. Did you know that, Kate?_

She turned to him, then, a frown making its way onto her features. "What?" she asked looking self-conscious.

He blinked owlishly. A billion questions at the tip of his tongue disappearing into thin air. He shrugged. "More coffee?"

Her narrowed eyes scanned his face, but he must have been carefully because she just smiled, her nose twitching adorably and nodded.

He smiled in return, and twitched his nose too, making her laugh and push him off her desk.

He glanced over his shoulder. Her eyes were following him, her smile a shy little thing.

Castle had come to realize that there were a lot of things he didn't know.

He did know a few things.

He knew that he wouldn't get those nightmares again anytime soon.

He knew that he'd started seeing her as Kate. Soft, beautiful and loving Kate. Loyal and caring friend, Kate. Vulnerable, flawed, perfect imperfection Kate. Radiant, graceful, strong Kate. Careful Kate. Tender Kate.

He knew that she had more layers than even she knew about.

He knew that he'd be willing to spend an eternity trying to find out the answers to all his unasked questions.

One thing he knew beyond doubt.

Rick Castle _knew_ that he was indubitably, irrevocably in love with Kate Beckett.

* * *

**A/N: **So this is obviously AU. It happens after Set up and Countdown. I've very happily done away with Josh in this universe. Not my usual dialogue-y stuff, but I guess I was in a poetic kind of mood?

Fellers kindly gave me a few prompts that probably have been completely turned on their heads.

I might continue this, but in a different style. Not sure yet. Sorry if it makes no sense :P. Oops? Thanks for reading!


	2. Chapter 2

**A/N: **Thank you all very much for your reviews! Sorry I haven't replied individually. Busy schedule. This is a short chapter, but hopefully you'll like it. And unlike the last one, there's loads of dialogue.

* * *

Castle noticed the haggard look on her face when she thought no one was watching her. He's always watching her. Not to be creepy or anything. Kate looked tired. She was paler than usual, so that even the make-up didn't effectively hide it. She'd been sipping at her coffee all morning, and every so often she'd bring her thumb to her temples, rubbing in circles for a few moments before getting back to work.

So when she sighed heavily, her lids closed, before heading towards the break room with her empty blue coffee mug, he spent only a couple of minutes wondering whether she needed space. He figured he was never good at giving space, and so he followed.

He found her sitting on the counter next to the coffee machine – unusual on its own – staring unseeingly at the blinds. He closed the door behind him and made his way to lean against the counter next to her. When he thought about it, she'd been looking progressively more tired over the last few days.

"Hey. You okay?"

She nodded, with a small smile that didn't reach her eyes. "I'm fine." At his skeptical look, she amended, "Just tired. And I may have a slight headache."

"Well, no more caffeine for you," he said, earning himself a glare and a kick to his knee.

"Ow!" he yelped, looking indignant. "It's for your own good, woman."

"Oh shush, that didn't hurt."

"Says you. At least you're not wearing your pointy heels today."

"Lucky you."

"And you're wearing your comfy jeans."

"This is getting creepy really fast," she countered, narrowing her eyes at him.

"You're dressed for comfort."

"Why are you keeping tabs on my wardrobe?"

"Research?"

"I stopped buying that excuse about two dozen cases ago."

"You're tired."

"Now you're just parroting me."

"That sounds kinky."

"Castle!" she said, looking exasperated.

"Okay," he said, turning towards her, trying not to feel guilty. "You're tired enough to forgo your heels, and wear comfort clothes, you have a headache that you're actually admitting to, which means it's worse than you give it credit for, and you've been reading the same page for the past thirty minutes. Clearly, you're not fine."

"Charming. What's it to you, anyway?" she muttered, still not really accepting the fact. She must have seen the hurt cross his features before he looked away, because she spoke in a softer tone. "Sorry. I shouldn't have – It's just an off day, okay? I'll be fine."

He turned back to her with a smile to let her know they were good, but shook his head too and reached out for her hand. "Kate, you helped me last week. Let me do the same?"

Her gaze shifted to their hands, his thumb gently caressing the back of her palm. "I may have been having some trouble sleeping, too." He withdrew his hand suddenly, and her face shot up sharply, puzzled. "Castle?"

"Is it because of me?"

"How'd you figure that?"

"Because you've been waking up in the middle of the night to help me," he said like it was obvious.

She reached out for his hand, shaking her head and replying with certainty. "No, it's not that. I've been tossing and turning, and waking up every hour or so."

"Nightmares?"

"I don't think so," she said, scrunching up her nose adorably. "At least, I don't remember if it is."

"Trust me, you'd remember. Okay, then what?"

She huffed and rolled her eyes. "If I knew that, I doubt we'd be having this conversation."

"Right, sorry."

"No, don't apologize. I should apologize. You're just trying to help. I'm being testy cause I'm tired."

"Aww, Beckett. You don't need to apologize. You're always testy with me," he said, grinning smugly.

"That's cause you always give me reason to be," she said, narrowing her eyes, and taking her hand away to fold her arms.

"See? You're getting back to normal already."

"You're ridiculous." The corners of her lips twitched upward.

"Ridiculously awesome."

"And delusional."

"Now you're just being mean," he pouted. "And just when I was about to offer an invitation to watch a movie at the loft this fine evening."

Her eyebrows shot up. "Did you miss the part where I'm extremely tired?"

"No," he drew out, "That's exactly why I'm inviting you."

"I don't quite follow."

"My plan is to tucker you out. It's ingenious in its simplicity."

"Uhuh," she said flatly.

"What? You have a better idea?"

"Yes! A hot bath, scented candles, soft music."

"That does sound better. We should do that."

"We?" she said, looking at him like he'd lost his mind.

"Of course. You're miserable."

"I don't need pointy heels to hurt you, you know," she said, glaring.

"And misery loves company," he said pointing his thumbs towards himself. "Company," he declared.

Kate snorted inelegantly, making him raise his eyebrow. "Really, Castle? _You're_ movie idea sounded more reasonable."

He grinned triumphantly. "See, I knew you'd get on board."

"Wait, what?"

"Always knew you're a smart woman."

"Castle, I didn't –"

"You should really get back to work, you know."

"But –"

"And no more coffee," he said sternly, backing away.

"Where are you going?" she asked as she slid off the counter.

"Home, getting stuff ready. See you soon," he said, grinning infuriatingly, and bolted before she had the chance to do more than gape at him.


	3. Chapter 3

**A/N: **Not sure when I'll post next. Have a long week ahead. Thanks for reading!

* * *

Exhausted as she was, Kate decided to leave her car at the precinct. She took a cab over to Castle's. It wasn't late, in fact, given the tedious nature of the case they were working on; early evening was a fantastic time to be able to get out of the precinct. It was early enough that she could spend a couple of hours with Castle, let him have his way – kind of – and then slink out citing exhaustion.

In having decided as much, she didn't really feel any force behind her decision. Every few steps she would pause – much to the chagrin of one poor unsuspecting civilian who nearly spilled his coffee thanks to running into her on the footpath outside Castle's building.

In the elevator, one of Castle's neighbors – presumably – tsk-ed at her incessant foot tapping.

Finally, at his door, with her fist raised and pulled back, ready to knock, she had a moment of doubt. Well, she'd been having multiple moments of doubt all day, but in that moment, the doubt overcame her decision.

Just because his conniving ways tricked her into coming to the loft for a movie didn't mean she had to do it. In fact, that's exactly why she shouldn't be coming to the loft. _No feeding the animals, Kate. _So what if they're cute, cuddly and just a little too charming? No!

She'd show him.

She turned to leave just as the elevator dinged on his floor again, and rushing out of it like she was on fire, was one Martha Rodgers. No, really. Her fiery orange and bright red dress made her look like she was cloaked in fire.

"Martha?"

"Katherine! What a delightful surprise?" Martha caught Kate's hands in hers own and spun Kate around twice and somehow she ended up facing the door. "Were you just coming to see Richard? Oh, darling, he'll be ever so happy," she said on Castle's behalf as she struggled to find her keys in her purse.

"Actually, I was just –" Kate paused looking for a good enough reason to explain what she 'was just' doing in their corridor. She was saved coming up with a ridiculous excuse – because any excuse would probably have been ridiculous – by an excited red-headed teen.

"Gram! Oh, Detective Beckett!" she lit up and to Kate's eternal surprise, grabbed her for a hug after she'd given one to Martha. More to her surprise, she was spun around – though a lot more gently than a few minutes ago – a full three sixty degrees so that she was looking to a fairly amused Castle headed her way. She turned back when she realized Alexis was talking to her, and she just missed some mumbling about 'leaving dad alone'. "It's so great that you're here, I wish I could stay in with you guys, but I have a test. You guys have fun, and if you watch something I haven't seen, could you make dad promise not to spoil me? Please, okay, thanks, bye!"

Or at least that's what Beckett gathered before she could even put a word in. And then Alexis was off like the Flash, and all Beckett could do was raise her hand lamely in farewell at the door, before it was being held in a firm grip by Martha and she was being spun again.

What is it with these spinning Castles?

"Goodbye, Katherine, darling. Don't worry about me; I just came to take my gloves. Richard, don't bother her too much," she instructed Castle.

So dizzy was she by that point that she swayed forward precariously, before colliding with Castle's firm, deliciously warm chest. His hands came up to grip her firmly around her back, and if he tugged her just a little closer, she pretended not to notice.

"Don't do anything I wouldn't do," she instructed a final time in a singsong voice before making her exit.

"We're safer not doing things you would do, mother!" Castle called out after her, chuckling.

There was a period of silence that should have been jarringly awkward, but it wasn't. She let her forehead drop to his shoulder in an attempt to stop the room from spinning. Waiting for a snarky comment that never came, she appreciated his measured silence, his steady breaths an anchor to regain her own.

"You okay?" he asked softly.

She pulled back, her forearms still on his chest, and looked in wonder at the concern that was so openly displayed towards her. "Yeah." She had to clear her throat, from sounding so breathless. "I can't believe I'm saying this, Castle, but you might actually be the least hyper person in your family."

He burst out with laughter, causing her to laugh along too, and pulled her in for a hug. "You're just saying that now," he said, calming down after a beat. "Until I prove you wrong again."

"It wasn't meant to be a challenge," she groaned and closed her eyes and heard him chuckle lightly in response. He shifted to brush a kiss to her cheek. An innocent enough, friendly, platonic kiss, that kind of lingered. If she shivered, it was because she was cold. That was all. When his nose nudged her cheek, lingered some more, and when she turned in response, unwittingly letting their noses bump each other, it was because she was still a little dizzy from it. From all the spinning, that was all.

"Hi," he croaked, before clearing his throat, finally pulling back, his hands at her elbows for a moment to make sure she was steady.

"Hi," she replied, ducking her head shyly.

"I'm glad you decided to come."

She shrugged. Now that she was here, she didn't want to tell him that she almost didn't. "You sound surprised."

"To be honest, I thought you'd cop out."

She fought the strange sense of hurt that seemed to bubble up in her, trying to cover it with humor. "No pun intended?" she smirked.

He beamed at her a little stupidly. Her stomach flipped a little stupidly, more so when he made as if to grab her hand, but thought better of it. "Come on," he said, tipping his head towards the couch. "Now that you're here, movie time," he said, rubbing his hands gleefully. "Pick out a movie." He indicated his vast collection on the shelves next to his TV.

She rolled her eyes. "Castle, I thought you left early to get things ready. I thought you'd have a movie in mind," she said a little absently even as she perused his collection, thumbing out various dvds before sliding them back in place.

"I did get things ready!" he defended. "We have two different flavors of popcorn, a whole selection of candies including MnMs, Nerds, Twizzlers, and more, and a couple of choices in soda. Oh, and a perfectly cozy nest on my sofa for some expert level cuddling."

She turned sharply at that, and raised one slender eyebrow critically at him.

It took him a moment to playback what he said. "Did I say cuddling? I didn't mean cuddling, I meant – well, okay I meant cuddling. But not with each other! With the throws, all soft and velvety, and fleecy. And, I'm – you're – you're laughing."

"Oh, Castle, you're so easy sometimes," she said through her smile, turning back to pick their movie.

"Cuddly too," he muttered under her breath.

"What?"

"Only for you, Detective," he said aloud.

"Hmm," she said with a nod, oddly pleased. "How about this one?"

"As you wish," he said, bowing his head cheekily.

She'd picked out 'The Princess Bride'. It was a classic, and just the kind of light movie she wouldn't mind watching again, even in her state of tiredness. Probably all the more appropriate for it.

He took it from her and went about setting it in his system while she made her way to his couch. It did look like a soft cottony heaven. She thought that she could, possibly, be willing to spend more than a couple of hours with him after all.

"Well, don't just stare at it longingly," he insisted, and added with a grin, "Let's watch movies all night… we'll just veg out in front of the TV."

"Hah!" she couldn't help herself, "Pretty Woman?"

"Of course I think you're pretty," he said patronizingly. With a hint of genuine thrown in.

"Don't be obtuse."

"Let's just say it's one of mother's favorites."

Going by his wince, she assumed that was probably true.

"Okay, then, Castle. Let's veg out. Lay like broccoli," she said, plopping onto the couch, drawing her legs up and getting comfortable, and patting the place beside her.

He sat down a lot less gracefully, and maybe closer than necessary, grinning at her like he knew it but didn't care.

"Maybe we should watch that one next," she said as the credits rolled.

The smile dropped right off his face, and she fought to hold her laughter in.

"Uh."

And she lost the fight, letting the tinkling laughter flow out of her. "Kidding."

"You're mean. No MnMs for you," Castle said with a pout, picking up the bag of MnMs and hugging them close to his chest, turning away from her in overt dramatics.

Kate bit down on the corner of her lip, wondering how far was too far. But he'd live. She moved closer to him, difficult in itself since they were already sitting with their sides mashed together. Shifting so that her knees fell to his thigh, she pulled the throw so it covered both of them, her hand sliding over his forearm as he moved to dig out a piece of candy. If his breathing was a little more erratic, it wasn't her fault. It was his own.

"You'd really deny me candy?" she said, batting her eyelashes.

"Serves you right," he said weakly, his throat bobbing visibly as he swallowed, turning so that he face to face with her.

Big mistake, she thought, fighting a smirk. Big. Huge.

Her fingers trailed slowly down his forearm to his hand, and his eyes left hers to follow their path before returning to her eyes.

"But I'm even sharing my blanket with you," she said, letting her nails scrape over the back of his hand.

"Technically it's my blanket," he said, his voice low and husky. Good.

"Didn't think you were so possessive," she said, her own voice starting to get husky.

To her surprise, he growled, feral and low. His eyes had darkened, and maybe she had gone too far after all. Maybe she should pull back. If she could.

His eyes were trained on her lips, his hand moving beneath hers so that she could feel the ripple of the small muscles under her fingers. Kate's eyes were glued to his, and she didn't noticed when he'd brought his hand to her lips, pressing gently.

She opened up, as if by reflex, and realized belatedly that he'd slid in a piece of chocolate.

"I can share," he croaked out. "With you."

She pulled back, thrown by the intensity of it all, still savoring the sweet chocolate melting on her tongue. It was supposed to be a little light banter. A little bit of teasing that got away from her – that ensnared not only him, but her too. He looked away from her when Fred Savage's whining got through to them. Only then did she notice that they had missed the very beginning of the movie. A glance at him told her that though he was looking at the TV, he wasn't really taking it in. His eyes were glassy, and his jaw tense, his nose flaring every couple of breaths like he was trying to regulate his breathing.

She shifted only slightly so that she was facing the TV more than facing him, but still what he may consider as cuddled up. "Sorry," she whispered, not sure why she was apologizing. Yet she knew exactly what for.

He looked at her then, his face softening, even smiling. His cheeks lifted up, and the corners of his eyes crinkled as he smiled at her. "I was gonna share, Kate," he explained adorably, though unnecessarily, settling the bowl of popcorn on his lap next to her knee.

"I know, Castle," she said with a smile, bumping her head onto his shoulder.

"Thanks for sharing the blanket. I tend to like it warm ever since –" he trailed off, knowing she'd understand.

Ever since the freezer incident, she'd taken to turning up her thermostat more than usual, and piling up the blankets in her bedroom. She hummed and shivered with the memory. "Me too."

"Maybe that's why you'd been waking up," he said nonchalantly.

A little too nonchalant. She narrowed her eyes at him, as she noticed his lips quirking. "I'm warm enough at night, before you offer."

"I was going to do no such thing. Why Katherine Beckett, I never!" he said, sounding affronted, before breaking out into a coy smile. "But I like the way you think."

She rolled her eyes, and poked him hard enough so he yelped and rubbed the spot. "Shut up and watch the movie," she said, unable to stop the little smile that betrayed her amusement.


	4. Chapter 4

Castle thought it was a beautiful night. A mixture of moonlight and Manhattan streetlights snuck its way through the space in his living room curtains, softly illuminating the dark wooden floorboards. The air carried a sort of sweet-salty tang from their collection of popcorn and candy. But it was a different scent that made Castle smile.

Cherries.

Kate had progressively gotten more comfortable through their evening. Her feet had finally ended up on the coffee table next to his, and her arm had somehow woven through the crook of his elbow. Though he teased her about it, he didn't actually think Kate to be the kind to snuggle. It was a pleasant surprise.

Somewhere along the way, she'd fallen asleep; his shoulder her pillow. He'd been careful not to move, to not even fidget until her breaths had evened out into a deep slumber. Not even after that. He was comfortable just the way he was.

But they'd been like that for a couple of hours; his neck sore and back stiff. Though she was in better shape than him, he didn't want her to wake up with cramping muscles. He reached out for the remote control to turn off the idle TV screen and sighed to himself in resignation.

With his free arm, he moved to cup her face, and called her name out gently to avoid spooking her. Kate stirred but didn't wake. She turned her head to nuzzle his shoulder after a cute little snuffle. He thought fleetingly whether he'd let it go, whether he could maneuver them so they'd be lying down on the couch more comfortably and just spend the night that way, but there was a nagging feeling he couldn't shake, that they weren't quite there yet.

"Kate," he called out a little more firmly.

She opened her eyes at that and pivoted her head just a fraction to glare at him weakly. "Five minutes, Castle."

"You can have much more than five minutes, but let's move you to the bed, huh?"

Her eyes shot open at that, eyebrow rising dangerously.

"Guest bedroom is all set up," he clarified.

Kate huffed, moving away from him. He felt the warmth seeping away. By the tiny shiver he noticed, because he had gotten so good at observing her, he thought she felt the same. "I should head back," she said softly, her fingers weaving through her silky hair, sliding them off her face.

"Stay," he urged, "please? You look exhausted, Kate. You have been exhausted, and it's not just today. You'll just get more awake on the way home."

To his eternal surprise, she seemed to actually be considering it.

"You know you want to." He nudged her shoulder gently, and the way her body seemed to sag gave away her decision. "Come on," he said, taking her soft warm hand in his.

He helped her up, and turned her towards the stairs, pressing lightly low on her back, his hand spanning across it. She didn't offer any resistance, didn't utter a word. It made him both happy, and just a little concerned, because it was unusual for her. It was unusual for her to let him take care of her, and he guessed that it was unusual for her to let anyone take care of her. He was honored that he got that chance, however small.

Before he knew it, they'd come to stand next to the bed. This was part of why he left the precinct early. Part of the stuff he needed to get ready. He'd changed the sheets, and cleaned the guest room. He'd set out a new toothbrush, sitting unopened in its package on the bathroom counter next to the sink. Kept fresh linen there too. It was all ready to welcome her. Help sway her decision, hopefully, if she didn't find it creepy. Only one thing he hadn't considered.

"Umm," he said ineloquently, "Stay here, I'll be right back."

"Mmf."

"Don't move."

"Okay."

"No running away when my back's turned."

"Castle!"

"Fine, yeah. Be right back," he said, only finally noticing that he still had her hand in his.

He practically flew down the stairs, into his bedroom, spending not more than a few seconds before he got what he needed, and raced back up the stairs.

He was happy that she'd only moved enough to sit down, staring blindly at the wall opposite her. "Here," he said a little breathlessly as he handed her one of his T-shirts and an old shrunken pair of sweatpants.

She took them from him with a smile. Even tired, she glowed. Or it was the effect of the low yellow light that cast her face half aglow, half in shadows.

Kate cleared her throat, indicating her discomfort. It was hard not to stare at her. He was tired too, and it made him a little sloppy. Less guarded. "Right, well. Good night. See you in the morning."

"Good night," she echoed, and just as he stepped out the door, she called his name so quietly he almost missed it. But he was attuned to her voice. To her breaths, her movements.

Still facing away from her, afraid to look back, unable to leave her be; he only allowed his head to turn slightly. Like a sunflower towards the sun. He was really tired. "Hmm?"

"Thank you."

Castle's lips twitched then. His eyes closed, head nodding just the once. He'd had doubts all day long since having "convinced" her at the precinct. All of those doubts flew out the window just then. "Always," came his reply, just as softly, and he knew she'd be wearing a smile just like his own.

* * *

It was later in the night that he'd awoken with the intense need to relieve himself. The three cans of soda were to blame. While returning from the en suite to his bedroom, he heard a noise.

His sleep addled brain and active imagination thought of ninja assassins, spies, covert CIA operatives, and the ever-famous cat burglars as possibilities. Whoever it was seemed to be foraging in his kitchen. Usually he would put it down to being Alexis or Martha trying and failing to be quiet, but neither of them were home. But, oh, Kate was.

Given how tired she'd looked earlier, he'd hoped she would've had an undisturbed sleep, but his great tucker her out plan seemed to have failed. Squaring his shoulders, Castle headed out of his room, determined to help her get back to sleep. Just as he was passing his bookshelves, he glanced at the living room, and squatted down while slapping his hand over his mouth to squash his yelp.

He'd been expecting an exhausted looking vulnerable Kate Beckett in his loft. Not the figure wearing a too-large black as night hoodie sneaking around as if looking for something. He knew it.

He knew it!

It was a somewhat sloppily dressed ninja assassin, and there wasn't anyone around to believe him. Well, there was Kate upstairs, but damn him if he let this fiend get to her. He grabbed a fencing sword from the stack next to the stairs leading to the first floor landing, and tip toed his way to the kitchen. Sloppy Ninja had been heading there from the living room when he first noticed through the bookshelves.

He ducked behind the counter when Sloppy Ninja turned to the cupboards, after a slight pause, thankfully facing away from him. To be fair, Sloppy Ninja was being very careful about opening and closing the cupboards, probably to avoid making noise. It was luck really, that Castle had heard anything at all earlier. Their recent slew of cases and his recent re-watch of Harry Potter's fifth installment had left him in a state of constant vigilance, as Mad Eye Moody called it. Clearly someone named Mad Eye Moody – fictional or not – had to be believed.

Castle had come up with the plan to corner Sloppy Ninja and then call out for Kate. He rounded the corner carefully, and rose to his full height, ready to brandish his fencing sword when Sloppy Ninja suddenly turned around, armed with a giant frying pan, raised and ready to strike.

They both yelped.

"Jesus, Castle, what the hell?"

"Kate?" he asked, recovering from the scare. He'd jumped a full foot back, one hand on his chest to calm his terrified heart, and the other still holding the sword. He lowered his sword hand to his side.

"Whom were you expecting?" she asked, glowering at him, putting the pan down on the counter and lowering the hood of the sweatshirt.

"Uh. Sloppy Ninja?"

"What?"

"Who were _you_ expecting?"

"I don't know. A burglar? You were sneaking around like one."

"Me? You're the one dressed like a – like a - "

"Sloppy Ninja?" she completed with a smirk.

"Well. Yeah! What _are_ you wearing anyway?"

"Uh. It was in one of the drawers upstairs, I thought it was yours," she said, ducking her head down, suddenly shy as she mumbled, "smells like you."

Castle carefully kept the sword leaning against the counter, and moved towards her, squinting as he got closer. "Oh yeah, that is mine. I was wondering where it went."

She huffed, scuffing her socked foot on the tiled kitchen floor.

"I got cold. Sorry."

"Don't be. Looks better on you anyway," he said with a smile.

Kate looked up at him, a tender look gracing her face. "Yeah, I totally rock the sloppy ninja look."

Even in the dark of the night, she noticed his blush. "Hey, cut me some slack. It's the middle of the night. Also, I _could_ be attacked by ninjas, you never know."

She shook her head, and smiled wider. "Sure, Castle. Ninjas set to invade your kitchen in the middle of the night in search of the mystical mu shu chopsticks of doom – it could happen."

He felt an odd mixture of indignation and awe that she would say that. Or even think it. Who was this Kate Beckett?

He must have been gaping too long, because he felt her hand gently close her jaw, and then ruffle his hair as she let out a hearty chuckle.

Castle had to clear his throat. She had no business looking that beautiful in the middle of the night, dressed in clothes twice her size.

"Did you have a nightmare?" he asked softly as her chuckles died down.

She shrugged. "I don't know. I just woke up, and I couldn't get warm, till I found this thing. Then I couldn't get back to sleep, so I came down for a snack."

"Still feeling cold?"

"Just my hands," she said, holding said hands out in front of her.

"Still hungry?"

Kate shrugged again. "I could eat."

"How about a PB&amp;J and a hot chocolate. Get you warmed up instantly," he suggested.

"Probably not healthy," she said, her biting her lip. She looked like she was waiting for him to talk her into it.

He obliged with a huff. "Really, Kate? Who has healthy food for midnight snacking? Live a little."

"Fine. Sugar overdose sounds great," she said, beaming as he immediately set about his new task with a proud grin.

She traced his every move as he gathered the pot, milk, and the rest of the things he needed. He didn't mind at all. He was reveling in the domesticity of it.

"Why were you awake? Not a nightmare?"

"No, no. Needed to pee," he said with a sheepish grin, earning him an eye roll.

"Told you to ease up on the soda."

"Yes, mooom!" he mocked, eyes rolling for good measure.

She gaped and socked him on the arm.

"Hey, ow! That hurt," he said, turning only to be leveled with a fierce glare. "Jeez, okay, sorry."

"Uhuh."

"Didn't have to hit me so hard."

"Oh, man up, Castle."

"Can I help that I bruise like a peach?"

"You'll live," she said, shaking her head at him even as she stepped closer.

"I'll be sore for days. Don't blame me if I can't carry your coffee cup tomorrow."

"He says as he continues to stir hot chocolate."

"It'll get sore, and achy, and bruise-y."

"Poor baby."

"You're not even apologizing."

"Don't hold your breath."

"Here I am, toiling away in the middle of the night for you, and what do I get in return? A sore arm is wh – wh – what are you doing?" he ended, with a loud gulp.

She'd inched close into his side, raising her hands onto his bicep. Her fingers slid under the hem of his sleeve, slowly sliding it upwards, exposing more of his arm. He tried to keep his eyes on the almost-done hot chocolate, but they kept darting to her.

He called her name, his voice strangled, breath stuttering when her nose bumped into the upper part of his arm, just below his shoulder where she'd socked him.

Castle noticed absently that she was at the perfect height, shorter than he was used to without her heels. Did she just breathe him in?

Her lips settled where her nose had been, just a second ago, and lingered to drop a tender kiss there. Castle moved his head, unable to stay still with having her so close to him in the quiet of the night. Just as he angled his head toward her, she pulled back. He shifted slightly so their faces were just inches apart. Her eyes strayed to the side, her hand lowering his sleeve back into place and smoothing it down as they gazed intensely at each other.

They heard a bubbling noise, and she took another step back, breaking eye contact, and extended her hand to turn off the stove. The moment was broken.

Though there was a kissing booboos quip somewhere in the back of his mind, he found himself unable to voice it. Found himself incapable of much more than returning to the mundane task of preparing their snack. She seemed to be having the same problem as she rounded the counter to sit herself down, as he slid a sandwich to her. She duck into it, while he got his, and divvied up the hot chocolate between them.

They ate in silence, Kate seated on a stool at the island, and Castle standing opposite her. He needed a moment to recover.

Both finished their sandwiches quickly, and Castle had nearly guzzled down his hot chocolate while Kate was cradling hers. Her thumb was absently stroking the mug, while she seemed deep in thought. He couldn't blame her.

He was about to ask her if she didn't like it when he realized that she was just taking her time. Delaying the inevitable moment that they'd have to part, and she'd have to try to go back to sleep. She was stalling.

Castle took the dishes and his mug to the sink, just rinsing them quickly, leaving them for washing later at a more decent hour. "Hey," he said softly, walking around to stand next to her.

"Hmm?" she said, not even turning.

"Kate."

She looked up at him reluctantly, her eyes looking suspiciously shiny.

"Something bothering you?"

She sighed, looking down to her mug again. Taking a large gulp to finish what was left, she set her mug down and turned in her stool to face him. He took a step closer so he was standing between her legs. It was intimate, and maybe too much. Maybe too little.

"I needed to check that you were alright."

"So you did have a nightmare?" he asked, feeling concerned.

She let out a deep breath and leant into him, much to his surprise. The stool was tall, so her forehead settled against the lower part of his chest. "I don't remember waking up from one," Kate said, as his arms came up and around her, drawing her closer into his warmth. "I just remember feeling cold, and I had this strong need to check on you."

"I understand," he said truthfully, running his hand over her back soothingly. "Why didn't you?"

"What do you mean?"

"Why didn't you check on me?"

"I did," she stated.

His hand paused in his surprise. "You were in my bedroom and I didn't notice?"

Kate sniggered. "Seems I'm stealthier than you are."

"I'll have to work on my stealth mode," he accepted.

"Hmm. You do that," she said, drawing back, his hands sliding across her back to settle on her shoulders.

"Yup. I'll sneak into your bedroom as many times as I need to."

She snorted.

"For practice, Beckett," he said, fooling no one.

"Right. You do know I sleep with a gun?"

"You might have mentioned it before."

"Be good to remember it," she mumbled, ending in a yawn.

"Oh, I remember it, alright. I just ignore it."

"Don't make me shoot you. Too much paperwork."

"Your concern is positively touching," he said, withdrawing his hands to his side.

"I'm nice like that."

"Yeah, you're a real saint."

"I must be, if I have the patience to deal with you."

"Ouch. You wound me."

"You'll live."

"I feel this strange sense of déjà vu. The good kind."

She rolled her eyes and pushed him away from her. Castle snagged her forearms and drew her off the stool.

He boldly dropped a kiss to her forehead – something he wouldn't dare do just a few weeks ago. But they'd crossed some invisible line, and it felt like there was no turning back. He didn't want to turn back. Judging by the fact that all his appendages were intact, she seemed to be allowing it at least. Maybe even enjoying it?

"Come wake me this time if you need to, alright? But for now, back to bed."

She looked to the stairs and then back at him, whining adorably, "Do I have to?"

He couldn't ever remember her whining like that. Although he could imagine her wanting to say that when she was told about him shadowing her. Castle chuckled with the thought. "Yes. It's not that far."

"Fine," she said, turning around and heading to the stairs like a woman on a mission. She paused on the landing. "Thanks, Castle. Night."

"Until tomorrow."

She smiled, turning away from him.

* * *

Her voice was almost angelic as it reached his ears, calling out his name. He felt like he was floating towards it, closer and closer.

He woke up suddenly, realizing it was more than a dream when he heard it again.

"Castle?"

"Kate?"

"What time is it?" he asked groggily.

"Ah, you've just been asleep for half an hour."

"Oh," he said, confused.

"Sorry, shouldn't have woken you."

"No! No, it's fine. You okay?"

"Hmm."

"What's wrong?"

"Couldn't sleep," she admitted, while picking at his blanket.

He blinked owlishly twice before scooting over and drawing the blanket up.

"Castle?" Her voice held both disbelief and longing, as did her face.

"Kate."

"What are we doing?" she asked, sighing. She sounded so defeated it hurt his heart.

Where he would have joked in another lifetime, he replied with the utmost sincerity instead. "We're helping each other get over a very traumatic event that could have ended our lives."

She looked up at him.

"Kate, we _saved _the city. But we nearly died ourselves. Twice. It's okay to be scared."

"I'm not scared," she defended, glaring at him.

"Then it's okay to not be okay."

She looked away from him, to his door.

They didn't do this. They were all about subtext and walls and cast iron defenses.

He lowered his head back on to his pillow, and moved his hand to rub at his eyes. He was so tired. She must be too. Why couldn't she just recognize it? But the fact was that she couldn't.

She couldn't recognize it. Couldn't recognize them.

And he would just have to deal with it like he always did. He applied just enough pressure to see stars. To keep the stinging in. To keep his eyes dry.

That's when he heard shuffling, and felt his blanket move.

He took his hand off his face, needing a second for his eyes to adjust.

Kate was sliding under the covers next to him. She smiled sadly at what must have been a look of complete astonishment, even as she adjusted his arm just where she wanted it. He let her. Couldn't really get it to function for himself. Her side was flush with his, the warmth spreading through all the way to his toes.

Castle couldn't take his eyes of hers. She leaned up just enough to place a kiss to the corner of his mouth, her thumb replacing her lips much too quickly.

"Talk tomorrow?" she asked softly, gazing at him tenderly.

He nodded, for lack of any other coherent response, and she smiled in return.

She nuzzled down into his chest, her arm banding across him, keeping him close.

He wrapped his arm around her as her leg coiled around his, drawing her even closer into his warmth.

There were a lot of questions unanswered. A lot of new questions that arose. What were they doing? Did either of them know? Maybe. What Castle and Kate did know, as they each closed their eyes, was that there wouldn't be any more nightmares that night. And if they were to return, the partners would face them together. This thing, budding and hopeful, had murky origins. One day there was nothing; the next it was something solid, sure and indisputable. They were something. Something inevitable, good and beautiful. It was powerful, this kind of knowledge.

* * *

A/N: Soooo. When I started this chapter, I hadn't expected to end the story, but, this is it. It felt very natural to end it here. (Suffice it to say, they lived happily ever after in that weird Castle-y fashion of theirs. Duh.)

Thank you for all the lovely reviews!


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